dplyr.spark

This package implements a spark backend for the dplyr package, providing a powerful and intuitive DSL to manipulate large datasets on a powerful big data platform. It is a simple package: simple to learn if you have any familiarity with dplyr or even just R and SQL, simple to deploy: just a few packages to install on a single machine, as long as your Spark installation comes with JDBC support -- or build it in, instructions below. The current state of the project is:

• most dplyr features supported
• adds some spark-specific goodies, like caching tables.
• can go succesfully through tutorials for dplyr like any other database backend^[with the exception of one bug to avoid which you need to run Spark from trunk or wait for version 1.5, see SPARK-9221].
• not yet endowed with a thorugh test suite. Nonetheless we expect it to inherit much of its correctness, scalability and robustness from its main dependencies, dplyr and spark.
• we don't recommend production use yet

Installation

You need to download spark and build it as follows

cd <spark root>
build/mvn -Pyarn -Phadoop-2.4 -Dhadoop.version=2.4.0 -DskipTests -Phive -Phive-thriftserver clean package

It may work with other hadoop versions, but we need the hive and hive-thriftserver support. The package is able to start the thirft server but can also connect to a running one.

dplyr.spark has a few dependencies: get them with

install.packages(c("RJDBC", "dplyr", "DBI", "devtools"))
devtools::install_github("hadley/purrr")

Indirectly RJDBC needs rJava. Make sure that you have rJava working with:

library(rJava)
.jinit()

This is only a test, in general you don't need it before loading dplyr.spark.

---

Mac Digression

On the mac rJava required two different versions of java installed, for real, and in particular this shell variable set

DYLD_FALLBACK_LIBRARY_PATH=/Library/Java/JavaVirtualMachines/jdk1.8.0_51.jdk/Contents/Home/jre/lib/server/

The specific path may be different, particularly the version numbers. To start Rstudio (optional, you can use a different GUI or none at all), which doesn't read environment variables, you can enter the following command:

DYLD_FALLBACK_LIBRARY_PATH=/Library/Java/JavaVirtualMachines/jdk1.8.0_51.jdk/Contents/Home/jre/lib/server/ open -a rstudio

---

The HADOOP_JAR environment variable needs to be set to the main hadoop JAR file, something like "<spark home>/assembly/target/scala-2.10/spark-assembly-1.4.1-SNAPSHOT-hadoop2.4.0.jar"

To start the thrift server from R, which happens by default when creating a src_SparkSQL object, you need one more variable set, SPARK_HOME, as the name suggests pointing to the root of the Spark installation. If you are connecting with a running server, you just need host and port information. Those can be stored in environment variable as well, see help documentation.

Then, to install from source:

devtools::install_github("RevolutionAnalytics/[email protected]", subdir = "pkg")

Linux package:

devtools::install_url(
  "https://github.com/RevolutionAnalytics/dplyr-spark/releases/download/0.3.0/dplyr.spark_0.3.0.tar.gz")

The current version is 0.3.0 .

You can find a number of examples derived from @hadley's own tutorials for dplyr look under the test directory, files databases.R, window-functions.R and two-table.R.

For new releases, subscribe to dplyr-spark's Release notes feed or join the RHadoop Google group. The latter is also the best place to get support, together with the issue tracker)